question

[low_delta]

You know all those little islands in the Pacific ocean, that have some palm trees and nice sandy beaches? Where does the sand come from?

Comments

[sunrae.livejournal.com]

Happy New Year!
Just checking about this morning...
Maybe the sand was shipped from the beaches of Lake Michigan.
Goodness know we have lot of it :)

On a wonderful New Year's Day

[serendipity.livejournal.com]

Silicon is everywhere, you know, not just here in Silicon Valley!

happy new year!

[low-delta.livejournal.com]

You have a lot more of it your side of the lake. Actual dunes! When I was a kid, we used to go over to Warren Dunes all the time. We usually took some sleds. Those dunes are huge.

Re: happy new year!

[sunrae.livejournal.com]

I live about 35 miles of so from there..you're right they are huge.
we have Mt. Baldy and the Indiana Dunes State Park right near me. Nothing more beutiful when you can see what's under all of the snow. :)

[banana.livejournal.com]

I think that (rather boringly) the sand came from the islands - rocks, coral and so on, smashed up by the sea. So maybe you could ask "why is it still there?"

well, yeah...

[low-delta.livejournal.com]

But I thought most of the islands were formed when coral reefs broke the surface, and coral is calcium.

As far as it remaining there, I guess the waves push it back up the beaches, like they do everywhere. But that's still rather mysterious (IMO).

Re: well, yeah...

[banana.livejournal.com]

The theory I heard is that the coral is there because there were normal islands there before (tops of undersea mountains, possibly volcanoes), and the coral grew around them. As the islands eroded (making sand particles), the coral was left behind to form an atoll.

I don't think that sand *has* to be made of anything in particular - calcium will do fine, though it may not last as long.

Maybe Ponti could sort this out for us.   ;-)